Into the woods: Invasive plants: An endpoint?

By

Ethan Tapper

My job as the Chittenden County forester can be broadly described as negotiating the relationship between humans and the forested ecosystems of Chittenden County. To this end, I serve as a resource for landowners, communities and individuals interested in forests, forest management and land stewardship. Through my work I have the opportunity to observe the “big picture,” the trends and forces that influence forested ecosystems in this corner of Vermont over time. One of the most disturbing of these trends is the threat posed by invasive exotic plants, which present a disturbing vision of the future of our forests. In my view, the presence of these species represents a theoretical endpoint in the growth and development of our forested ecosystems.

In the forested ecosystems of the northeastern United States, we are blessed with a remarkably diverse suite of native species that regenerate readily following disturbance events. Our forests utilize a simple scheme to do this: When some trees die, others capitalize on the opportunity to establish and grow. While this may seem obvious, in many parts of North America, the regeneration of native trees is no easy thing. In some areas of this continent, landowners must replant harvested areas for these forests to regenerate at all. It is the exceptional diversity and richness of our forested ecosystems that make this blessing of natural regrowth possible. We humans benefit from this capacity by having new trees constantly establishing and growing, ready for us to tend, harvest and enjoy.

In the midst of this abundance, it is easy to ignore invasive exotic plants as they establish and slowly spread through the understory of a forest. We put off their removal, saying we will address the issue when these species become a problem. However, when trees in the overstory of a woodlot succumb to natural mortality, become mature or start to decline, we are forced to deal with these problematic species head-on. I have seen many cases where the loss of an overstory, which would normally be rewarded with the establishment of a diverse crop of native seedlings, leads to the dominance of invasive plants and little else. Unless they are removed, these invasive plants will occupy these areas, inhibiting the forest’s natural regeneration process, indefinitely. This is the “endpoint” to which I refer, a moment at which the cycle of life in a forested ecosystem is arrested into the indefinite future.

Taken broadly, I see this trend applying to many of our forests, given enough time and inactivity. So, what do we do? The days may be gone when any disturbance will automatically trigger an abundance of native regeneration, but this doesn’t mean our forests are going away. There are ways to control these species using hand pulling, cutting, smothering and, yes, herbicide, that will allow native species to establish in areas where they were once outcompeted by invasives. In some cases, planting native tree species, in addition to invasive species removal, can help give your next generation of trees a head start against these fast-growing invasives. If we are willing to give this issue the time and the attention it deserves, we are certainly capable of growing healthy forests stocked with native trees in a post-invasive landscape.

These days, when I see a single invasive plant on a landowner’s property, I tell them they have an invasive plant problem. The truth is all of us, even those of us who have never seen one of these plants, have an invasive plant problem. My dream is to see concentrated, community-wide efforts in the removal of these species, in recognition of the fact they don’t stop at property lines and neither do our forests. I hope we can use these actions as a springboard to talk about how to make the forests in our region, and all those reliant on them, healthy into the indefinite future.

Click on vtinvasives.org for more information.

Ethan Tapper is the Chittenden County forester for the Vermont Department of Forests, Parks and Recreation. He can be reached at his office at 111 West St., Essex Jct., at 585-9099 or at ethan.tapper@vermont.gov.